<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="app">
        <div>
            <p>请选择你要购买的书籍</p>
            <ul>
                <li v-for="(v, i) of arr" :key="i"> {{ v.name }} <button @click.prevent="add(i)">买书</button></li>
            </ul>
            <table border="1" width="500" cellspacing="0">
                <tr>
                    <th>序号</th>
                    <th>书名</th>
                    <th>单价</th>
                    <th>数量</th>
                    <th>合计</th>
                </tr>
                <tr v-for="(v, i) of arr" :key="i">
                    <td>{{ i + 1 }}</td>
                    <td>{{ v.name }}</td>
                    <td>{{ v.price }}</td>
                    <td>{{ v.count }}</td>
                    <td>{{ v.price * v.count }}</td>
                </tr>
            </table>
            <p>总价格为: {{ totalBooks }}</p>
        </div>
    </div>
    <script src="../vue.js"></script>
    <script>
        const app = new Vue({
            el: '#app',
            data: {
                arr: [
                    {
                        name: "水浒传",
                        price: 107,
                        count: 0,
                    },
                    {
                        name: "西游记",
                        price: 192,
                        count: 0,
                    },
                    {
                        name: "三国演义",
                        price: 219,
                        count: 0,
                    },
                    {
                        name: "红楼梦",
                        price: 178,
                        count: 0,
                    },
                ],
            },
            computed: {
                totalBooks() {
                    return this.arr.reduce((sum, v) => sum + v.price * v.count, 0)
                }
            },
            methods: {
                add(id) {
                    // console.log(this.arr)
                    this.arr[id].count++
                }
            }
        })
    </script>
</body>

</html>